Narrative:

Departed FBO at sfo in SVFR conditions (800' scattered, 1 3/4 mi visibility) northbound along highway 101 en route to hunter's point to pick up some cargo, I encountered a low level fog layer (that was not there 40 mins earlier) at fuller's point. Fuller's point has hills along one side, a multiple story bldg on the other and several sets of wires across the freeway. Descending to 300' AGL, I found myself at the base of the fog. It was a bit clearer just past the shoreline toward hunter's point. Thinking it better to turn around there, I continued past the shoreline (my airspeed at this time was approximately 10-30 KTS). Over the water I turned the aircraft around to return to sfo. When I did, I discovered that the fog layer had moved further east, further reducing visibility and in many areas lowering the ceiling. With visibility contact of the water and less than 1/2 mi horizontal visibility, I started back to sfo after informing them of my intentions. In the reduced visibility, I lost contact of the freeway and became confused about the actual location of the freeway and the airport. Trying to locate the freeway I turned west, but realized that with the hills in that direction I should stay east, so I turned back to the east at which time sfo gave me a radar vector toward the field and cleared me to land at FBO. At this time visibility at the northwest corner of sfo was less than 1 mi. Not being able to locate FBO, I landed at the air cargo operation hangar, then followed txwys to FBO where I waited for the fog to dissipate. I believe my first mistake was to decide to continue to the water to turn back. With the far's stating that helicopter's may be operated in less than 1 mi visibility if at a speed that allows adequate time to avoid obstructions and with visibility reference to the ground, I believe that a dangerous situation may occur under a variety of conditions such as the conditions that I encountered--although I feel that however inadvertent, I should have turned back earlier. I feel that the existing regulations make the possibility of these conditions easier to encounter. I know that my personal WX minimums have changed quite a bit.

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Original NASA ASRS Text

Title: HELICOPTER PLT ENCOUNTERS DETERIORATING WX. BECOMES DISORIENTED IN ATTEMPT TO RETURN TO DEP ARPT. RECEIVES VECTORS.

Narrative: DEPARTED FBO AT SFO IN SVFR CONDITIONS (800' SCATTERED, 1 3/4 MI VISIBILITY) NBND ALONG HWY 101 ENRTE TO HUNTER'S POINT TO PICK UP SOME CARGO, I ENCOUNTERED A LOW LEVEL FOG LAYER (THAT WAS NOT THERE 40 MINS EARLIER) AT FULLER'S POINT. FULLER'S POINT HAS HILLS ALONG ONE SIDE, A MULTIPLE STORY BLDG ON THE OTHER AND SEVERAL SETS OF WIRES ACROSS THE FREEWAY. DSNDING TO 300' AGL, I FOUND MYSELF AT THE BASE OF THE FOG. IT WAS A BIT CLEARER JUST PAST THE SHORELINE TOWARD HUNTER'S POINT. THINKING IT BETTER TO TURN AROUND THERE, I CONTINUED PAST THE SHORELINE (MY AIRSPD AT THIS TIME WAS APPROX 10-30 KTS). OVER THE WATER I TURNED THE ACFT AROUND TO RETURN TO SFO. WHEN I DID, I DISCOVERED THAT THE FOG LAYER HAD MOVED FURTHER E, FURTHER REDUCING VISIBILITY AND IN MANY AREAS LOWERING THE CEILING. WITH VIS CONTACT OF THE WATER AND LESS THAN 1/2 MI HORIZ VISIBILITY, I STARTED BACK TO SFO AFTER INFORMING THEM OF MY INTENTIONS. IN THE REDUCED VISIBILITY, I LOST CONTACT OF THE FREEWAY AND BECAME CONFUSED ABOUT THE ACTUAL LOCATION OF THE FREEWAY AND THE ARPT. TRYING TO LOCATE THE FREEWAY I TURNED W, BUT REALIZED THAT WITH THE HILLS IN THAT DIRECTION I SHOULD STAY E, SO I TURNED BACK TO THE E AT WHICH TIME SFO GAVE ME A RADAR VECTOR TOWARD THE FIELD AND CLRED ME TO LAND AT FBO. AT THIS TIME VISIBILITY AT THE NW CORNER OF SFO WAS LESS THAN 1 MI. NOT BEING ABLE TO LOCATE FBO, I LANDED AT THE AIR CARGO OPERATION HANGAR, THEN FOLLOWED TXWYS TO FBO WHERE I WAITED FOR THE FOG TO DISSIPATE. I BELIEVE MY FIRST MISTAKE WAS TO DECIDE TO CONTINUE TO THE WATER TO TURN BACK. WITH THE FAR'S STATING THAT HELI'S MAY BE OPERATED IN LESS THAN 1 MI VISIBILITY IF AT A SPD THAT ALLOWS ADEQUATE TIME TO AVOID OBSTRUCTIONS AND WITH VIS REF TO THE GND, I BELIEVE THAT A DANGEROUS SITUATION MAY OCCUR UNDER A VARIETY OF CONDITIONS SUCH AS THE CONDITIONS THAT I ENCOUNTERED--ALTHOUGH I FEEL THAT HOWEVER INADVERTENT, I SHOULD HAVE TURNED BACK EARLIER. I FEEL THAT THE EXISTING REGS MAKE THE POSSIBILITY OF THESE CONDITIONS EASIER TO ENCOUNTER. I KNOW THAT MY PERSONAL WX MINIMUMS HAVE CHANGED QUITE A BIT.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.